How do weeds affect plant growth

How do weeds affect plant growth

 We all face this problem of weeds outgrowing our crop plants. Invasive weed starts covering the soil surface and completely takes over the native species of plants. They are natural enemies of cultivated crops. Ecological management of exotic plant species is necessary or the weed populations can create an imbalance. 

The most common problem caused by weeds is competition between crops and weeds. A crop plant may not receive enough sunlight or water, or weeds may outcompete them for nutrients. Weeds take up nitrogen from soil. They also take up phosphorus, potassium, magnesium, calcium, sulfur, boron, copper, zinc, molybdenum, manganese, iron, chlorine, fluorine, and selenium.

They normally produce a rosette of leaves close to the soil surface the first year, then flower, mature, and die during the second year which constitutes the life cycle of weeds. Weed seedlings of late-emerging weeds continue growing. 

Definition of a Weed

A weed is any plant growing where it isn't wanted. Some plants we consider weeds include common purslane, dandelions, thistles, mustard, common chickweed, common ragweed, common cocklebur and pigweed.

“What are Weeds Doing in My Field?”

In nature, plants compete with each other for sunlight, water, space, and nutrients. This competition makes it difficult for some plants to survive and flourish. Agricultural weeds are common everywhere. Human activities play a crucial role is establishment of a new weed species in an environment. 

Imported Weeds and Invasive Exotic Plant Species

The most common invasive plant species in North America are Japanese knotweed and Himalayan blackberry. Both were introduced from Asia into Europe and North America during World War II.

Understanding what Makes Weeds Tick

Planting native plants helps reduce the spread of invasive species. It’s important to know where your weeds come from. If they came from a garden center, it may not be necessary to remove them, but if they came from a wild area, it should be removed immediately.

Weed-Crop Interactions: Competition and Allelopathy

A Crop seed is generally planted at or near the optimum soil temperature needed for quick germination--a temperature that is also ideal for some weed seeds.

The most common weed problem is one caused by competition between crops and weeds. For example, a field planted with corn will likely produce fewer weeds than a field planted with wheat. This is because corn has a high demand for nitrogen and phosphorus , which are found in fertilizers. Nitrogen is used to build proteins, and phosphorus is needed to build bones and teeth. On the other hand, weeds don’t compete well with grasses, so farmers often plant grasses alongside their crop.

Compete for Nutrients

If you want to grow healthy plants, you should try to keep soil nutrients available to them at all times. To do this, you should apply fertilizer regularly throughout the growing season. The soil organic content should be maintained. Fertilizer is applied either through drip irrigation, broadcast application , or using a granular form that is mixed into the soil. Crop stage is important to consider while fertilizing. 

Parasitic Plants

The most common parasitic plants are the morning glory , which grows from seedlings and has white flowers, and the clematis vine , which grows from seedling and has purple or pinkish flowers. Both species grow quickly and produce seeds easily. They often take over gardens by spreading through underground stems called rhizomes. Clematis vines can climb walls and trellises. Morning glories can climb fences and trees. Sensitive crops cannot compete with invasive weeds.

How do weeds affect plants

A weed is any plant that spreads without permission and takes over other plants. Some weeds are invasive and can cause damage to crops and property. Other weeds are beneficial but may compete with desirable plants.

Weeds can hurt more than just your plants

The common way people control weeds is by using herbicides. These chemicals have herbicide activity,  kill the roots of the unwanted plants and prevent them from growing but this is injurious to the soil life, humans, animals and the environment. Alternatively biological weed control agent can be used or biocontrol agents should be used.

Weed Management

There are many different types of control of weeds and weed management techniques available. These include manual removal, mechanical control , and chemical control. The type of strategy you choose depends on the type of weeds you have, what you have access to, and whether you want to grow crops in the future.

Planning your crop rotations

Rotating crops between beds allows you to minimize soil compaction and conserve nutrients. It also helps prevent diseases from spreading among plants. The impacts of weeds are reduced during crop rotation. The annual weeds and the late emerging weeds are disturbed and this helps the control of weeds.

Developing your weed management strategy

The best way to develop a weed management strategy is by working closely with your local gardening expert such as the one from UrbanMali. They will give you advice based on your area, farm practices, and crop type. They may also suggest some products you could try.

Among many strategies, the topmost is to be sure to cultivate as shallowly as possible to prevent bringing new weed seeds from below layers to the soil surface.

On the soil surface and within the first few inches of soil, herbicides can be volatilized, adsorbed to soil particles, taken up by plants, broken down by sunlight, or degraded by soil microorganisms and chemical reactions.


Pre-planting involves applying fertilizer to your soil before planting seeds. It’s important to apply nutrients at the right rate, because too little or too much can cause problems later on. If you’ve got a problem with weeds, pre-planting is one of the most effective ways to control them. The soil life and the soil organic matter should be maintained.


Transplanting is the process of moving plants from one location to another. This might involve taking cuttings from existing plants, or transplanting seedlings into larger pots or directly into the garden.

Early in-crop

In-crop refers to planting crops before they reach maturity. It's normally done in spring or early summer, so that the plant has enough time to develop fully before it goes into production.

Late in-crop

The late in-crop method involves planting seeds at the end of June or early July. This allows the plants to grow through the hot weather of August and September, which improves yield.

Post-harvest weed control

After harvest, it's important to remove weeds from the field before they germinate. If weeds are allowed to sprout, they will compete with crops for water, nutrients and sunlight. In addition to being unsightly, weeds can spread diseases and cause soil erosion. Temperature extremes such as cold temperatures decreases weed growth. 

Cultural methods

There are many cultural ways to weed out unwanted plants. For example, some people consider dandelions to be weeds because they don't look like flowers. Others may think that all grasses are weeds, but not corn. Some people think that radishes are weeds, but not lettuce. In some places wild carrot is considered as a weed.

Mechanical and physical methods

These are often used in conjunction with chemical herbicides, which kill the plant by causing it to die from lack of water. They can also be used alone if the weeds are small, and the area is well drained. The mechanical method works best for annual weeds, such as dandelion, clover, and crabgrass.


Herbicides are chemicals designed to control unwanted plants. Most herbicides are systemic and they may take several days to weeks to affect the plant. Some herbicides are contact killers, meaning they only affect the part of the plant that comes into direct contact with the spray, which are called contact herbicides. The pesticide labels or the herbicide labels specify the herbicidal activity. Contact herbicides include Roundup, 2,4D, triclopyr, and glyphosate. The herbicidal activity affects the plant tissues. 

Chemical herbicides are poisonous to all living things of the ecosystem. Biocontrol agents and biological weed control agents should be used. 

Biological weed control agent 

A biological weed control agent (also called biological control agent) is any organism that eats or parasitizes other organisms. These organisms are usually insects, nematodes, fungi, bacteria, viruses or algae. Biological weed control agent works in such a way that these bacteria or fungi causes root injury or infects the roots of the weeds and thereby checks the spread of weeds. They act as selective herbicides. This is a natural method to control weeds with ecological management as well. 


FAQ on Weeds

How do weeds harm human beings?

Most weed killers contain glyphosate, which has been linked to health problems including cancer, birth defects, and kidney damage. Glyphosate is not registered for use on food crops in the US, but it is widely used on non-food crops like grassy landscaping, golf courses, farm fields, and roadsides. It's often applied in combination with other herbicides.

When do Weeds Become a Problem?

Weeds are a problem when they takeover the native species and create an imbalance in the ecosystem. These weeds are generally exotic plant species which are introduced to a new environment.

Can Weeds Damage Your Lawn and Garden?

Yes, weeds can damage your lawn and garden. They compete with grasses for sunlight, water, nutrients, and space. In addition, they can cause soil erosion and damage to your lawn and garden.

How can I keep weeds out of my garden?

If you want to keep weeds out of your yard, you will need to remove them from the area where you want to plant. This may involve digging them out by hand or using a tiller. 

How do weeds affect crop yields?

Weeds compete with the crop for nutrients in the soil and generally grows faster than the crop plant thereby affecting the crop yields.

What are perennial weeds?

Perennial weeds often have underground stems that spread under the soil surface or, like ground ivy (Glechoma hederacea), have creeping stems that root and spread out over the ground. They are persistent and grow back again the following year. 

What are some of the common weeds? 

Some plants we consider weeds include common purslane, dandelions, thistles, mustard, common chickweed, common ragweed, common cocklebur and pigweed.


Get Help From an Expert

Need help in controlling weeds? Get in touch with us at or call us at  918880482000 for any queries. We can help you with your garden.